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    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script type="text/javascript">
       let number =  18
       let person = {
           name:'张三',
           sex:'男'
       }
       Object.defineProperty(person,'age',{
           value:18,
           enumerable:true, //控制属性是否可以枚举，默认值是false
           writable:true,//控制属性是否可以被修改，默认值是false
           configurable:true //控制属性是否可以被删除，默认值是false
       })
       console.log(person)
    </script>
</body>
</html>